Looper drive for buttonhole sewing machines or the like



July 29, 19 69 E. WIDER 3,457,888

LOOPER DRIVE FOR BUTTONHOLE SEWING MACHINES OR THE LIKE Filed Jan. 5, 1967 2 Sheets-Sheet i NEEDLE BAR H q 0 I6 0 w 55 o l3 0 o 1, IO 7) I4 \U I5 150 A INVENTOR EBERHARD UNDER ATTORN EY5 July 29,1969 E. WIDER 3,4 7 8 LOOPBR DRIVE FOR BUTTONHOLE SEWING MACHINES OR THE LIKE Flld Jan. 5, 1967 2 Sheets-Sheet 2 SPEED INCREASING PROVISIONE/L 1 PIGS SPEED INCREASING PROVISIONS SPEED INCREASING PROVISIONS I NVENTOR EBERHARD UNDER $2641 x Q m ATTORNEYS United States Patent 3,457,888 LOOPER DRIVE FOR BUTTONHOLE SEWING MACHINES OR THE LIKE Eberhard Wider, Leouherg, near Stuttgart, Germany, as-

signor to Union Special Maschinenfabrik G.m.b.H., Stuttgart, Wurttemberg, Germany Filed Jan. 5, 1967, Ser. No. 607,449 Claims priority, application Germany, Jan. 8, 1966,

U 12,349 Int. Cl. D05!) 1/06, 1/10, 57/04 US. Cl. 112201 16 Claims ABSTRACT OF THE DISCLOSURE Looper drive provisions for chain-stitch, zig-Zag sewing machines employing two loopers including two crank or eccentric drives driven at a speed ratio of 1:3, motlon combining provisions driven from each of the two crank or eccentric drives and combining the two motions therefrom which differ in speed and looper drive provisions connecting each of the two loopers and the motion combining provisions to impart to the two loopers the combined motion output from the motion combining provisions. Preferably the two motions combined at an amplitude ratio in the range 1:7 to 1:9 and the sewing machine needle is driven at twice the speed of the lower of the two aforementioned motions.

The invention relates to a drive mechanism for loopers cooperating in alternate succession with the needle of a chain-stitch zig-zag sewing machine.

Chain-stitch Zig-zag sewing machines wherein two loopers cooperate in alternate succession with the needle have become known as short seam automatic apparatus. These are especially the machines designed for buttonhole sewing. Sewing machines of that type are adapted to produce a single thread chain stitch, and each looper during its turn, seizes the needle thread at one side where the needle penetrates and carries it to the other side of the needle penetration, thus to there form a loop into which the needle will enter. For this purpose there is required a movement of each individual looper, which extends approximately 90 of a sewing cycle as it carries the looper from one side to the other, which stops there for the next 90 and then carries the looper back through another 90, whereupon there follows again a stop phase of about 90. In order to achieve these movements, control cams are used as looper driving means in hitherto known sewing machines. These control cams in use are responsible for an uneven running of the machine and also a limitation in its revolutions. Said uneven running results essentially from the fact that the looper movement is started off with jerks which are caused by the sharp changes in the shape of the contour of the control cam,

which sharp changes are also responsible for very large acceleration.

The present invention serves the purpose of improving the quietness and smooth running in chain-stitch zig-zag sewing machines embodying loopers cooperating alternatingly with the needle. The engineering problem to which the invention is addressed is that of providing a driving mechanism for the loopers of such machines wherein a harmonious movement is introduced.

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This problem is solved essentially by providing that each looper is driven by the combined cooperating movements of two crank means or drives, driven in a ratio of 1:3, whereby the needle drive receives double the revolutions than does the crank drive revolving at the fewer revolutions. In this kind of drive harmonius, sinus shaped movements of two crank drives are superimposed, which due to the transmission ratio and the particular selection of a suitable throw of the crank drives induce a movement which corresponds to the required movement of the loopers cooperating alternatingly with the needle. In the arrangement, the amplitude of the movement imparted to the loopers by the crank drive that revolves at a higher speed, is about of the amplitude of the movement of the other crank drive superimposed upon said first amplitude. For practical purposes, the amplitude of the movement imparted to the looper by the crank drive that revolves at the higher speed lies between and of the amplitude of the movement imparted to the loopers by the other crank drive.

Depending on the displacement of the field of penetration, in the case of increasing of the width of the cross stitches, either symmetrically or unsymmetrically in relation to the center position of the needle, both loopers can be driven by the same crank drives, or also by separate crank drives. In an arrangement wherein the loopers are driven by the same crank drives, different movements of the two loopers may be obtained by changing of the lengths of the connecting elements following in the train of driving connections after the crank drives which is particularly advantageous in the case of an unsymmetrical displacement of the needle penetration area. In addition, said connecting elements following the train of driving connections after the crank drive means are arranged and constructed in such a manner that they will arrive at the position of their maximum or minimum stroke during the phases of stoppage resulting from the superimposed amplitudes of the crank means or drives, in order to influence favorably the phases which are essential for the stitch formation. In an arrangement wherein each looper is driven by a separate crank drive, one can additionally achieve deviations of the movements by varying the throw of the cranks. Moreover, the possible change of the angular position of the crank drives will permit a phase displacement of the amplitudes. Thus, it becomes possible to adjust the correct movement of each single looper individually.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings.

In the drawings:

FIGURE 1 shows a buttonhole sewing machine embodying the invention and viewed from the front.

FIGURE 2 is a vertical cross section taken on the line A+B in FIGURE 1 and shows a gear mechanism for the drive of the loopers.

FIGURE 3 is a vertical cross section taken on the line CD on FIGURE 1.

FIGURE 4 is a schematic presentalion of the drive.

FIGURES 5 through 7 are schematic presentations of additional possibilities of design.

The buttonhole sewing machine herein shown as an example of embodiment of the invention includes in the customary manner, a needle 1, which moves up and down and laterally to and fro with a needle bar 2, a material clamp 3 and a knife 4. The drive for these elements-is arranged in a housing 5, in which the drive for the two loopers 6 is also located, said loopers cooperating alternatingly with the needle.

In the illustrated embodiment, a shaft 8 is driven by the main shaft 7 at a ratio of 2:1 for the introduction of the material feed movement. In a similar manner driving motion is imparted to the needle bar 2 by the shaft 7 at an increased revolution ratio of 2:1. Driving of the needle bar 2 by the shaft 7 may be effected by any of a number of suitable or known and conventional needle bar driving provisions, generally indicated by the numeral 51 in FIG- URE 2 and the needle bar driving provisions 51 may be driven at the increased revolution ratio of 2:1 by gear provisions similar to the gear provision shown in FIG- URE 2 interconnecting the shafts 7 and 8. Additionally, the shaft 7 has secured thereto a crank or counterweight 50 that drives a planetary wheel cooperating with a sta tionary internal gear 9 secured to the base of the machine by three screws 9a, 9b and 9c. The number of teeth between the internal gear 9 and the planetary wheel 10 is in a ratio of 4:1, which results in a ratio of 3:1 of the revolutions of the driving shaft 7 relative to the planetary wheel 10. The planetary wheel 10 has affixed thereto an eccentric cam 11, which is encompassed by a bearing lug 12 of a connecting rod 13. The connecting rod 13 is connected with a pair of bell crank levers 15 and 150 via a ternary element 14. The bell crank levers 15 and 150, are respectively connected by way of connecting rods '16 and 16a and lever arms 17 and 1711 with looper rock shafts 18 and 18a. These looper rock shafts 18 and 18a respectively carry the loopers 6 and 6a adjustably.

These parts, available in duplicate after splitting up of the gear mechanism, serve essentially for the purpose of controlling the acceleration and the delay of the loopers favorably in those phases of the movement which are decisive for the faultless formation of stitches, and for this purpose they reach, in this phase, their maximum or minimum stroke position. In addition, there are differences which distinguish the duplicate parts from each other, in particular in the length measures, which are different on the bell crank lever 15a, the lever arm 17a and the connecting rod '16:: as compared to parts 15, 17 and 16, and these differences are necessary in order to obtain a different movement for each of the loopers 6 and 6a. These differences in the construction of the parts serve the purpose of taking into consideration the movement of the loopers in the case of an unsymmetrical displacement of the position of the needle penetration area upon changing of the width of the cross stitches.

The radius of the circular path of the center of the planetary wheel 10 is larger than the eccentricity of the cam 11 by about 9 times. Through this choice of the transmission ratio and of the throws of the cranks, the center of the bearing lug 12 moves on an essentially quadratic path 19, as shown in dot and dash lines in FIG- URE 4. This path is changed preferably by reducing the eccentricity of the eccentric 11 relative to the radius of the circular path of the center of the planetary wheel 10 to a ratio of about 1:7, as a result of which the shown straight lines of the generally quadratic path 19 will receive a slightly concave curvature. Through the slight curvature of a side of the quadratic path 19, toward the inside, the movement imparted to the loopers 6' and 6a will be influenced favorably, in order to achieve proper cooperation between the loopers and the needle at the proper times.

It is to be understood that the gear mechanism shown in one particular embodiment can be varied within the scope of this invention in order to achieve the desired movements for both loopers. Thus, for example, it will be possible, according to schematic presentations in FIGURE 5, that two cranks 21, 22 driven at a ratio of revolutions of 1:3 and that the connecting rods 23, 24 are connected with one another by means of a balance beam or single tree 26. The crank 21 may suitably be driven from the shaft 7 at the lower speed and rotary motion may be imparted to the cranks 22 by any suitable or conventional and known speed increasing provisions, generally indicated by the numeral 25, which may simply include gearing provisions selected to provide the aforementioned 1:3 rotary speed ratio. Said balance beam 26 is thereby guided for sliding movement in a slide guide 27. A connecting rod 28 is jointedly connected to said balance beam 26 in a train of connections for driving the rock shaft 18, which train of connections comprises similar connecting members as are shown and discussed in connection with FIG- URE 4. That is, the connecting rod 28 drives the ternary element 14 which, in turn, drives the bell crank levers 15 and 15a. The bell crank levers 15 and 15a, again, are connected with the looper rock shafts 18 and 18a via the connecting rods 16 and 16a and lever arms 17 and 17a. As illustrated in FIGURES 2 and 3, the loopers 6 and 6a are driven from the shafts 18 and 18a, respectively.

FIGURE 6 shows a possible alternate version of the schematically shown driving arrangement illustrated in FIGURE 5. Here, too, a balance lever or singletree 29 receives driving movement from cranks 21, 22 via connecting rods 23, 24. Once again, the crank 21 may be driven from the shaft 7 and the suitably selected or conventional speed increasing provisions 25 may be employed to drive the crank 22 from the shaft 7 at the desired 3:1 rotary speed ratio. Said balance lever is also guided in a slide guide 27 but it is not connected with a ternary element through a single connecting rod as in FIGURE 5, but has two connecting rods 31, 31a, the one 31 being articulated to the bell crank lever 15 for the purpose of driving the looper rock shaft 18, and the one 31a is jointed to the bell crank lever 15a for driving of the looper rock shaft 18a. The driven ends of the connecting rods 31, 31a are mounted adjustably in a slide guide 32. Through shifting of the points of articulation of the driven ends of the connecting rods 31, 31a in the slide guide 32, it is possible to adjust the amplitudes of the driving movements of the grippers 6, 6a individually. Altenatively, this adjustment can be accomplished through a possible selection of different lengths of said levers 15, 15a, connecting rods '16, 16a and lever arms 17, 17a. Again, in FIGURE 6, elements similar to those discussed hereinabove with respect to FIGURES 15 are similarly referenced and the bell crank levers 15 and 15a, driven from the connecting rods 31 and 31a, respectively, are further connected with the looper rock shafts 18 and 18a via the connecting rods 16 and 16a and lever arms 17 and 17a. The looper rock shafts 18 and 18a again drive the loopers 6 and 6a as best illustrated in FIGURES 2 and 3. In the modification shown in FIGURE 7, a crank 33 is connected with a ternary element 35 via a connecting rod 34, to which bell crank levers 36, 364: are articulated. The swiveling points or fulcrums of the said bell crank levers 36, 36a are not fixed, but are respectively articulated each to one bell crank lever 37 or 37a. The bell crank levers 37, 37a are respectively connected with connecting rods 38, 38a which are respectively driven by the cranks 39, 39a. The cranks 39, 39a have triple the speed of the crank 33, however, only about /7 of the throw of crank 33. The speed and amplitude relationships again provide the rotary speed and amplitude ratios discussed hereinabove and once again the driving members, here constituting the cranks 33, 39 and 39a may be driven in a fashion similar to that discussed hereinabove. That is, the crank 33 may be driven from the shaft 7, as illustrated, and the speed increasing provisions 25 may be employed to drive the cranks 39 and 390 from the shaft 7. As in the previous figures, similar elements are similarly referenced and the bell crank levers 37, 38 drive the looper rock shafts 18, 18a, respectively, via the connecting rods 16, 16a and lever arms 17, 17a. The rock shafts 18 and 18a drive the loopers 6 and M, respectively, as illustrated in FIGURES 2 and 3. The connecting rods 38, 38a are attached adjustably to the bell crank levers 37, 37a in order to permit changing of the etfective length of the arms of the bell crank levers 37, 3711 that are connected with said connecting rods. By means of such an arrangement of the drivingmechanism for the loopers 6, 6a, it is possible to adjust individually the amplitude as well as the phase position of the movement derived from each individual crank for each looper. This possibility of adjustment can be realized also in the embodiment shown according to FIGURES 2 through 4, by reason of the fact. that the planetary wheel 10 of FIG- URES 2 and 3, carries on its pivot stud two exchangeable eccentrics which are adjustable in their angular position, each on its respective pin, and connected through a connecting rod with one of the bell crank levers 15, a.

It is to be understood that in the embodiments herein shown by way of example, not all possibilities of the invention have as yet been exhausted, the scope of the invention opening the possibility to still more variations.

Thus, among other things, it is also possible to impart superimposed movements to each of the two looper rock shafts 18, 18a, said superimposed movements being derived from respective pairs of separate crank drives, each of which may be individually adjustable in such a manner, that both its amplitude as well as phase position, can be changed relative to the other crank drives.

What is claimed:

1. In a looper drive for a sewing machine of the type including a reciprocatab'le needle and at least one rotatable looper; the combination comprising first means for providing a first rotary motion at a first speed, second means providing a second rotary motion at a second and higher rotary speed, means driven from both said first and second means for providing rotary motion for combining said first rotary motion and said second rotary motion and means driven from said means for combining for applying the combined motion therefrom to the at least one rotatable looper.

2. The combination according to claim 1 wherein said means for providing a second rotary motion comprises means for providing said second rotary motion at a speed of approximately three times the speed of said first rotary speed.

3. The combination according to claim 2 wherein the second rotary motion provided by said second means has an amplitude of movement and approximately the range A through /8 of the amplitude of said first rotary motion provided by said first means.

4. The combination according to claim 1 wherein said first and second means comprise first and second eccentric drive means, said second eccentric drive means providing said second rotary motion having an amplitude of movement at least approximately through A; the amplitude of movement of the first rotary motion provided by said first eccentric drive means.

5. The combination according to claim 1 wherein said first means for providing a first rotary motion comprises a drive shaft and first eccentric means comprising a crank mounted on and driven by said drive shaft, said second means for providing a second rotary motion including a planetary gear mounted on said crank, a stationary ring gear in engagement with said planetary gear, and second eccentric means affixed to said planetary gear, said means for combining said first rotary motion and said second rotary motion including a connecting rod having one end driven from said planetary gear and a remaining end coupled to said at least one looper.

6. The combination according to claim 1 wherein said first means for providing a first rotary motion comprises first eccentric means including a first crank, said second means for providing a second rotary motion comprising second eccentric means including a second crank, said means for combining said first rotary motion and said second rotary motion including a balance beam having opposite, ends thereof coupled to said first and second cranks and said means for combining said first rotary motion and said second rotary motion further comprising a connecting rod attached to said balance beam intermediate said opposite ends thereof and coupled to said at least one looper.

7. The combination according to claim 6 wherein said means for combining said first rotary motion and said secondrotary motion further comprises guide means for guiding movement of said balance beam.

8. The combination according to claim 6 wherein said means for combining said first rotary motion and said second rotary motion further comprises a further connecting rod attached to said balance beam intermediate the ends thereof for driving a further rotatable looper.

9. The combination according to claim 8 wherein both said connecting rods are adjustably located with respect to said balance beam at their points of connection therewith.

10. The combination according to claim 1 wherein said first means for providing a first rotary motion comprises first eccentric means including a first crank, said second means for providing a second rotary motion including second eccentric means including a second crank, said means for combining comprising lever means coupled with said at least one looper, and having a movable fulcrum, means connecting said first crank with said lever means for pivoting said lever means about said fulcrum and means connecting said second crank with said movable fulcrum for moving said fulcrum.

11. The combination according to claim 6 wherein said means driven from said means for combining includes at least one swingably mounted bell crank lever connected with said at least one looper and a solitary element supported by and pivota-lly connected to both said connecting rod and said bell crank lever.

12. In a looper drive for a sewing machine of the type including a reciprocatable needle and first and second rotatable loopers; the combination comprising first means for providing a first looper driving motion at a first speed, second means for providing a second looper driving motion at a second and higher speed, means for combining said first and second looper driving motions and means for applying the combined first and second motions from said means for combining to said first and second loopers.

13. The combination according to claim 12 wherein said means for combining comprises connecting means driven from both said first and second means for providing looper driving motion, said means for applying the combined first and second motions including first and second swingably mounted lever means, means connecting said first swingably mounted lever means with a tfirst rotatable looper shaft, means connecting said second swingably mounted lever means with a second rotatable loper shaft, and means interconnecting said lever means and said connecting means.

14. The combination according to claim 13 wherein said connecting means driven from both said first and second means for providing looper driving motion comprises a connecting rod, said means interconnecting said lever means and said connecting means comprising a solitary element pivotably connected to each of said connecting rod and swingably mounted lever means.

15. The combination according to claim 13 wherein said first means for providing a first looper driving motion includes rotatable crank means, said second means for providing a second looper driving motion comprising a planetary gear mounted upon said crank means for rotary movement therewith, a stationary ring gear meshed with said planetary gear and eccentric means afiixed to said planetary gear and bearing thereon one end of said connecting rod.

16. The combination according to claim 12 wherein said second means for providing a second looper driving motion provides said second looper driving motion at ap- 5 proximately three times the speed of said first looper driving motion and at an amplitude of movement in the range of approximately through approximately ,4, the amplitude of movement of said first looper driving motion.

8 References Cited UNITED STATES PATENTS 1,558,182 10/1925 Kiewicz 112157 1,589,625 6/1926 Carlson 112157 RICHARD J. SCANLAN, JR., Primary Examiner US. Cl. X.R. 112-157 

